It was a lot more complex than that. There were the mobilization timetables. More intricate than a Swiss watch. If you were going to mobilize, you had to mobiilize.
Mobilisation is one of the excuses made.
There is a difference between mobilising and invading neutral Belgium. It doesn’t require any more to supply your army and keep them in the field when mobilised and sitting on the border than it does when they charge off and murder civilians in a neutral neighbour.